Funding for this research was provided by:
Headquarters Research Institute Project of the Company (T945-151920)
National Natural Science Foundation of China (31701424)
Open Project of State Key Laboratory of Crop Biology (2019KF06)
Received: 19 July 2021
Accepted: 26 November 2021
First Online: 13 December 2021
: All data in this study came from the internal data management system, and the author had access rights. The study only involved data statistical analysis, without field investigation of pig farms.
: Not applicable.
: The authors declare no competing interests.